Maintaining up-to-date information in a wide variety of areas is very important to many people. These people often desire to be alerted to time-sensitive events and information. Content providers generate content for notifications, which are then delivered to one or more subscriber electronically (e.g., via electronic mail). For example, a news organization may provide notification content relating stock prices, breaking news, weather conditions, traffic conditions, etc. A subscriber's expressed interest to receive electronic notifications for a particular class of content is generally called a notification subscription. Such subscriptions often are made between the end subscriber and the content provider that sends the notifications. Event-driven notifications of this type are often referred to as alerts or event notifications.
A notification service typically consists of a client tier or front-end server that provides a subscriber interface to a subscriber, and a middle tier that includes a plurality of load balanced back-end servers that can access a data tier to identify relevant events for a particular subscription. Disadvantageously, due to the three-tiered architecture in conventional notifications networks, the client tier requires contiguous notification of events that occur on the data tier but is only able to communicate with the server tier. However, because the server tier consists of a plurality of servers in which a balancing component is implemented to distribute the load experienced by each of the plurality of servers, the client tier is incapable of maintaining affinity to any single server in the array when the connection is disrupted. As a result, when a disruption in service occurs the client tier is not guaranteed reconnection to the same back-end server, and the client tier has to establish a new subscription. Unfortunately, the new subscription will likely be hosted by a different one of the array of servers and, thus, the subscriber can miss notification of events occurring during the disruption in the notification service.